A NH4F interface passivation strategy to produce air-processed high-performance planar perovskite solar cells

The simple assembling process and lower manufacturing cost are crucial for wide application of perovskite solar cells. In this work, we report an efficient interface passivation strategy for preparing high-performance planar perovskite solar cells, which does not require well-controlled moisture and oxygen atmosphere. A NH 4 F solution-based additive is introduced to passivated TiO 2 electron transfer layer, which offers reduction of oxygen-induced defects and residual surface hydroxyl groups , and lower trap state level. Using a typical planar structure of FTO/NH 4 F-TiO 2 /CH 3 NH 3 PbI 3 /Spiro-OMeTAD/Au, the champion device achieves a power conversion efficiency of 15.61%. After 28-day durability test, the device with NH 4 F-treated TiO 2 storing in air without any encapsulation exhibits a little efficiency loss (<10%). Our work demonstrates a generic approach to develop air-processed efficient planar perovskite solar cells by interface engineering for future commercialization.